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Written by Daniel Gwartney, M.D.
02 September 2018

16NN191

Testosterone Boosting Supplements

Muscle Growth & Sexual Benefits

 

 

This article will approach the herbal and dietary supplements marketed with the claim to boost natural T. Of course, the implication is that the boost will result in elevations above the threshold needed to increase muscle mass and strength, which is in the range of 700-1,100 ng/dL.1 Well, let’s just see about that.

 

Recall that natural T is produced in the body in specialized cells in the testes (balls) called Leydig cells. The production is monitored and regulated by two glands in the brain called the hypothalamus and pituitary. This system maintains circulating total T in a range that varies up and down, with about a 30 to 50 percent difference between the peak (highest concentration) and trough (lowest). When T is low, the hypothalamus directs the pituitary to release a stimulating hormone into the bloodstream that increases steroidogenesis in Leydig cells (T production). When T increases to the upper limit determined by the hypothalamus, it stops the pituitary signal, and the Leydig cells motor down to an idle. This is when everything is working right. There are conditions and injuries that can cause low T production, including inflammation, type 2 diabetes, trauma, iron overload, hormonal and metabolic disorders, etc.

 

The Potency of a Rock Star

Most supplements are marketed to suggest that they will give a man the sexual potency of a rock star. This is actually a pretty easy claim to meet, if there is not a pathologic condition present that impairs a man’s ability to achieve and maintain an erection. The T threshold to maintain an adult male with a prior history of sexual interest in a state whereby he is capable of being aroused and erect is fairly low. In fact, many men are capable of maintaining intimate affairs with their spouse or partner with total T concentrations (ng/dL) in the 200s.2 One study showing a significant positive effect of a multi-ingredient product designed to aid in sexual function for men (with mild erectile dysfunction but adequate T) failed to show any difference in serum (blood) T, either between groups or over time. Thus, sexual “enhancement” is not dependent on testosterone boosting in most men.3

 

With the advent of PDE5-inhibitor drugs (e.g., Viagra), the erectile function is readily supported, and sexual interest in humans is much more complex than it is for lab mice … well, except for college freshmen, perhaps. Sexual desire and arousal in humans is produced by social and environmental cues as much as any physiologic priming via T surges or pheromones. Thus, all these herbal sexual enhancers are generating as much response by adding a visual cue and reinforcing behavior, as much or more than any bioactive ingredient that may (or may not) be present. Absent an existing pathology, if a person expects to be hornier or more sexually potent, generally he is— the very definition of the placebo effect. Further, many such products have been found to be adulterated with PDE5-inhibitor drugs or antidepressants.4 A recent analysis of 150 (!) sexual enhancement, dietary supplements found nearly two-thirds contained pharmaceutical drugs, including PDE5-inhibitors (e.g., Viagra) and others.

 

“Full Throttle Ahead” for Muscle Growth

For the bodybuilder/athlete/weightlifter, the goal is supporting and enhancing the training response to resistance exercise, or increasing competitive ability on the playing field. Again, the threshold for such effects is much higher than needed to promote sexual desire, arousal or erections. Young men see rapid changes in muscle mass and skeletal frame during adolescence. This is the effect of markedly high peaks in T, as the regulatory system is adjusting to the change from an essentially gender-neutral childhood to the sexual priming of adolescence. Total T concentration can exceed 1,000 ng/dL during the cascading spikes generated by a healthy metabolism and “full throttle ahead” regulatory axis. This is the threshold noted to be necessary for muscle growth.1 Further, a recent paper suggests that in men receiving testosterone replacement therapy (TRT), those who receive it via injection (T esters) gain a greater response in bone density and muscle mass due to the temporary supraphysiologic peak in the first two days, post-injection.5 Thus, any muscle-promoting T booster would need to induce a pronounced surge that may exceed the ability of the Leydig cells to provide— particularly if the gentleman is aging, or has a history or recent exposure to anabolic-androgenic steroids (AAS).

 

There are familiar, and not so familiar names in the litany of supplement-based T boosters: Tribulus terrestris, maca, horny goat weed, Eurycoma longifolia (jack), DHEA, D-aspartic acid, fenugreek and a litany of others.6 In nearly every case of supplement-based T boosters, the product is a multi-ingredient formulation. The few that have attempted to broach the market solo, especially the sports nutrition market, have failed. In part, this is because some were never going to work; in others, the product may have a beneficial effect, but only for men with intact testicular function who suffered from low T. Stand-alone products have not been successful at boosting T concentration in young studs with raging hormones. This does not mean they may not be effective at boosting T in men with low T, or may have an effect on increasing desire, arousal or erectile function.

 

Reviews From the Weight Room and Bedroom

Multi-ingredient products are difficult to assess, particularly when no independent testing is reported. Most reviews focus on consumer response in the weight room or the bedroom. Satisfying as such examples may be on a personal level, they do not provide conclusive evidence of a testosterone-boosting effect. This requires, even if it is paid for or performed by the company, a financial commitment and relationship with a clinical lab to draw and assay blood samples. Again, the pulsatile nature of T production means that sampling has to be performed using pooled samples or controlled conditions. This is not done. Some companies have reported pre- and post-workout (and supplementation) T concentration, but this is not valid. Again, it is a single time-point sample, and resistance exercise by itself raises T.

 

Certainly, there is logic behind the rationale that T production during times of physical stress (e.g., high-intensity training, extreme dieting, overtraining, stressful conditions, etc.) would drop without the support of certain supplements. As glutathione (an antioxidant) levels drop with increased stress, or exposure to certain pollutants affects the function of the Leydig cells in the testes, or the antioxidant status of the hypothalamus is affected by sleep deficiency or disruption of the circadian function of melatonin, certain supplements may offer aid in reducing a subsequent decline in T production.7 These include NAC, taurine, grape seed extract, melatonin, zinc, magnesium and certain B vitamins.

 

Testosterone boosters rarely consider protective nutrition, and instead offer ingredients used to support sexual function, either in animal studies or traditional medicine. Two exceptions are DHEA and D-aspartic acid. DHEA is a steroid molecule, and the only androgen (by structure) that escaped being designated as a controlled substance by the DEA. Testosterone is produced from cholesterol by a chain of enzymatic reactions, one step of which involves the formation of DHEA followed by androstenedione. In women, DHEA acts as an androgen due to the low concentration of T; this may be true in the elderly as well. Studies have looked at DHEA as a precursor (or prohormone) to T production, and found it to have a mild positive effect in women and the elderly (who have low T production), but no effect in young men. In fact, DHEA and androstenedione (the next molecule produced in the T production chain) can increase estradiol (estrogen) in young men, and lower the T-to-estrogen ratio.8

 

D-aspartic Acid and Tribulus terrestris

D-aspartic acid has been known in animal studies to be involved in seasonal increases in T production, to promote mating. It was a study looking for nutritional support for infertile men that reported dramatic increases in T that sparked the short-lived market entry.9 Attempts at increasing T in young, healthy men to build muscle failed. Studies reported no benefit in strength or hormonal values in groups supplemented with D-aspartic acid.10 Yet, when looking at the original study, and others that followed, it became clear that the only men seeing benefits were those who were marginally T sufficient. In other words, only those who were low or low-normal saw an increase, and that did not reach the threshold for muscle growth. It did work for function of the sexual axis, though. D-aspartic acid may have value, just not for a young man with normal or high-normal T.

 

Of the botanically sourced T boosters, the ubiquitous name is Tribulus terrestris, or Trib. Trib launched onto the market to sensational early sales with strong marketing and a “first-to-market” positioning. Unfortunately, it was only after years of sales that published research came to the general consensus that Trib was ineffective at raising T in humans.8

 

Great Expectations on the Rise

Rather than troll through the myriad of other ingredients with claims of increasing T, two ingredients that have some, but not conclusive support for increasing T in healthy, young men who are not T deficient or insufficient are addressed. Also, there are one or two multi-ingredient products that are formulated by men whose scientific background is credible, but as I have not seen any independent efficacy studies, it is hard to determine their actual value.

 

Trigonella foenum-graecum is known by the friendlier name of fenugreek. Fenugreek has been attached to a panacea of positive effects, including improving glucose tolerance (or insulin sensitivity), lowering LDL cholesterol, suppressing appetite, inhibiting the formation of new fat cells and protecting the liver and kidneys. This is always a suspect trait, despite the published studies supporting these claims. Yet, mechanisms have been identified for some of these properties, so this supports further scrutiny of the claims of T boosting from fenugreek extract. Additionally, in rats, it has been shown that fenugreek is absorbed, has a half-life of 40 hours and is distributed slowly.11 It also penetrates the blood-brain barrier, a filter to protect brain cells from adverse effects. This may mean that fenugreek builds up over time; this may result in a delay of several weeks before a therapeutic concentration is reached in relevant tissues, or it may warn of the possibility of toxic concentrations being reached over time. In accordance with this, toxicity studies in mice showed a relatively high dose is required for a single lethal dose, but when dosed over 28 days, lethal effects were noted with a lower, though still considerable dose.12 Thus, it is difficult to recommend use of fenugreek products, long term.

 

Fenugreek has various fractions, some of which contain bioactivity. Within these fractions, certain molecules have been identified that offer a rationale for effect. Fenugreek was reported in a 2011 paper to strongly affect numerous enzymes systems in several important tissues (e.g., liver, kidney, brain, heart, muscle).13 Note, this effect was only notable for diabetic subjects (rodents), and no appreciable change was seen for normal animals. Also, it was noted that fenugreek increases the activity of cellular antioxidants. Recall that Leydig cells in the testes generate free radicals, and function is preserved in overstimulated (with hCG) rats with NAC, a precursor to the antioxidant glutathione, and other antioxidants.7,14

 

In a study of healthy young men performing resistance training, fenugreek was associated with a greater increase in free testosterone than displayed by the placebo group, though total T was unchanged despite being in the low-normal range.15 Performance in lifts was not impressively different, with the only statistically significant finding being aided by a wide variance in the control group for reps to failure. If the proof is in the pudding, fenugreek is a bland vanilla based on this study.

 

Lastly, there is a mushroom called Cordyceps sinensis that is present in many T boosters. Again, there is some support for a T-boosting effect from this ingredient, but it does not happen for young healthy weightlifters to any relevant degree.16 However, men who are near an overtrained state may avoid a lowering of T, as well as post-exercise increase in the catabolic hormone cortisol, by supplementing with the cordyceps extract combined with another botanical extract called Ganoderma lucidum.17 Note, T in the resting state was not dramatically increased.

 

Many Promises, But Talk Is Cheap

The field is full of promises, just like commercials during an election year. However, at this time, there does not appear to be a strong candidate for a supplement-based, single ingredient for boosting T in healthy young men. Certainly, for those in the low-normal or low range, or individuals hovering on the brink of overtraining, some benefit may be realized. The sexual boost is nothing to laugh about for those suffering from borderline or low T, but for most of this audience, that is not relevant. Multi-ingredient products will have to prove via published research that they have somehow broached the physiologic barriers to avoid supraphysiologic T, but that has not yet happened conclusively.

 

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